Process for purifying oil by distillation



1951 c. J. EGGER ETAL PROCESS FQR PURIFYING OIL BY DISTILLATION 2SHEETS-Sl-IEET 1 Filed July 9, 1945 I N VEN TORS MT- Wmw ,QAMJLM- M MNov. 13, 1951 Filed July 9, 1945 C. J. EGGER ET AL PROCESS FOR PURIFYINGOIL BY DISTILLATION 2 SHEETSSHEET 2 m? BYWH- 1N VEN TORS "d lation "a dp-s ce nequipment f for carrying out "the processes, have Patented Nov.13, 1951 UNITED :STIAT ES PATENT OF success :FQIR mrrrmo some) .DIS MIQN Charles J. *Egger and Robert H. 'Webster, Gleveland, Ohio"; assignorsto The Buokeye Laborae tories Corporation, a corporation .ofJOhio.JippiicationJuljB, 194'5,"Sei'ial'No. 603,856 7 I l claim.

Qu i vent on rel e ineen ra it d t l I and v more 'p;articu1arly toapparatus and process for separating iiuids of divergent "boilingpoints.

.iIn recent ear he as e velopment of 'iiaslh-distillation and alliedprocesses "for handling easily decomposable fiuid in Processes, and

bss l tieve qp d' ee hw rsi c ur as recovering of hy-prodrsct organiccompound; cleaning-'andrecovery ofused and contaminated oils aslubricating "and rol-lingoils; and the dehydrating and d egasifying offluids. *-Manyof these processesand the eguipment for the proc--esseshhave operatedwith only apart o'ff-the system employing-the-fiash-disti1lation principle while others were directed almostin-their-en- -tirety to t-he "flash-distillation principle. Further,although at first analysis they=may appear quite similan-two wide 1ydivergent principles are followed in operating various-types offlash-distillation equipment. First of these,=is--theprocess whichattempts 1:0 vaporize all but the extremely high :boiling point:constituents and sol-i'dsf Ihis process -=attempts--to turn I all --ofthe fluids enteri-ng the still into gases l for subsequent .selectivecondensation. In this type-of equip- .mentiand-sprocess, the gasesleaving ithe still are .generally :.strained :through a ;.scrubbing:medium of .loose materials in order :to :retain .:.any entrained solidmatter and aunvaporized heavy liquid material. i- I he second method,isto apply only enough heat to vaporize unwanted constituents and permit-the remaining constituents to be removed fromthe still as a liquid.

Itis-the second mode of-operation to which-our invention relates. In thepast, many' -attempts have been made to se parate fluids of Widelydiavergent boiling points'by pumping them at fa .high pressure into alow pressure zone and atomizing the fluids-in order that a maximum:amount ofasurfacearea might bespresented to the infiuence ofthelowpressure zone, and thereby =.thr ow the more volatile f constituent intogaseous phase and thus be removed from the higher boiling pointconstituents. =-Hdwever, fit

is always found that a considerable"percentagepf "the "material desiredto 'be separated out was alway found t fin she r osiu t whe us nthe-standard equipment -for this process.

After id r blezsiud a deve menthwe have discovered: that he weakness ofthe present k QthPQ hQs QI the ia u i resq riiz "t n d IfQ- im yi g 321.extreme 331156 amount of sensibleheatabsorbed"by liquid ma-'terials-when volatilized 'cally as the heat of vaporization. a found,thatthe amountof heat absorbed loythe -constituentsheing volatilized isso great-that fthe rne ii9 .Fi flui s 91 ,isl versn tor the removal ofcontaminants f 2 i h and expanded. Thefheat absorbed 'by thevolatilization is known techni- 'We have temperature within the stillwas oftentimesfre- 'duced to 'a' temperature insufiicient to --cause volatilization of the incoming impurities. Therefor, these impuritiesremain with the treated materials leaving the still. Further, it

has been found that after 'a-tomizing the contaminated or mixedmaterialja complete separatio n has "not loeen 5 accomplished by the*time the spray is recollected; and therefore requires a longer exposureto the" ifeduced pressure of the still. However, while beingiurtherexposed to the reduced pressure area, 'the newsman be maintained at ahigh temperature lever iri'order tooontinue to supply the latent leat'of 'i'apori- "z'ation required for 7 the remaining volatileconstituents." That is, if the atomized fluids are allowed to contact acold-surface,'orreturnover cold surf-aces to-asumpfor collection, "thevolatilecons'tituent's 'haveno chance to volatilize "and therefor remainwith the tre'ated materials; We have-found that-inorder toeffetacomplete and satisfactory separation of these volatile inaterials from 4the less volatile materials, the distillation zone into which thematerials areato'rnized, must be maintained at substantially thesame'temperaturelevel at allftimes, and the walls of the ohaniber,andcther surfaces which'the fiuids'might strikeor touch -must also bemaintaine'd at-substantially the -same constant' te'r'n- "perature.

Also, we have discovered that in separating YTlier Q m pom; Q l fi isf tg t ro v .aproces Lfq th Subs ntiall ther object of Q "additional *heat"to Mia/mussrleated conglomeration of fluids of divergent boiling pointswhile being distilled at sub-atmospheric pressures and while in thefinely dispersed state to obtain complete vaporization of all thevolatile components of the conglomeration desired to be removed, and toprevent condensation of the vaporized volatile components within thedistillation chamber.

Another object of our invention is the provision of spray atomizing aconglomeration of fluids of divergent boiling points into asub-atmospheric pressure chamber and thereafter interrupting the sprayby means of a fluid film exposing device capable of collecting theatomized spray and dispersing same over a multitude of tortuous pathsurfaces to increase the length of time which the conglomeration ofmaterials is exposed to the action of the sub-atmospheric pressure.

Another object of our invention is the provision of supplying heat ofvaporization and thermal energy of expansion by direct heat to thevaporization area in which the expansion is carried out.

Another object of our invention is to provide a-process and apparatusfor isothermal flashdistillation to separate a conglomeration ofmaterials of divergent boiling points.

Other objects and a fuller understanding of our invention may be had byreferring to the following description and claim taken in conjunctionwith the accompanying drawings, in which;

Figure 1 is a cross-sectional view taken along the line I-l of Figure 2;

Figure 2 is a longitudinal cross-sectional view taken along the line 22of Figure l;

Figure 3 is a cross-sectional view taken along the line 33 of Figure 4;and

Figure 4 is a longitudinal cross-sectional view taken along the line 44of Figure 3.

To achieve a separation of fluids of divergent boiling points mixedtogether in a conglomeration, such for example, as fluid dissolved influid,

, gases dissolved in fluid, and mixtures of fluid, or -any combinationor combinations of the aforesaid types, it is necessary to use someconvenient form of distillation, and all known methods of commercialtreatment contemplate the use of this type of physical action. Manymeans have been devised to accomplish this separation rapidly,completely, and effectively, but all have comprehended the separationbeing done by distillation of considerable quantities of theconglomeration. Conesquently, an appreciable time interval elapsesbetween the introduction of heat and pressure change, and the completionof the removal of the volatile portion. Also, to accomplish finalremoval of the last traces of the vola- .tile portion from a quantity ofthe original conglomeration, thermal energy is applied at an increasingrate. While this is being done, conditions exist in the conglomerationfrequently favorable to breaking down some of the desirableconstituents, with formation of additional undesirableconstituents andproducts of lower molecular weights. These break-down products are oflower boiling points, usually sufficient in degree ing mixtures willfrequently cause the final product to be considered not totallysatisfactory in regard to desirable physical characteristics.

If, however, a comparatively small amount of the conglomeration besubjected to a distillation process at sub-atmospheric pressure, and ifthis quantity be extended to present the greatest possible surface tothis sub-atmospheric action, it is found that the separation is achievedwith a degree of completeness not previously possible, and in a periodof time which does not permit any observable degradation of thedesirable constituent of the conglomeration. In order to present maximumsurface, it is necessary either to present a continuous film ofnegligible thickness, or to disperse the conglomeration in exceedinglyfine globules. The existence of either of these forms must exist for aperiod of time sufiicient to assure the separation of the lower boilingpoint constituents from the higher boiling point constituents of theconglomeration. From the standpoint of control of operating conditions,it has been found to be more satisfactory to present discreet globularparticles to the combined action of heat and reduced pressure, than toextend a continuous film, only one surface of which can be presented tothe sub-atmospheric pressures and spaces.

One of the features of our invention is the provision of heat for thewalls of the chamber independently of theheating of the conglomerationto be treated. For example, we have found that if the conglomeration isfirst raised to a temperature sufliciently high to assure enough heatenergy for the heat of vaporization for the volatile portion, it isentirely possible that the volatilization of the more volatileconstituents by distillation will be practically complete even thoughthe vaporization is carried out in a chamber that is not supplied withour improved heated wall condition. If however, the vaporized portionshave occasion to come in contact with the walls of the chamber which areat a much lower temperature, condensation occurs on the walls and anappreciable amount of the volatile constituents will flow down the sidesof the chamber and combine with the less volatile constituents whichhave been freed from the more ,volatile constituents by the fractionaldistillation which has already occurred. The final result is thereforthat the volatile portions are removed from the conglomeration beingtreated, and subsequently reincorporated to some degree.

We have found that by maintaining the walls of the chamber in the areaof the spray and evaporation, and preferably by maintaining all of thewalls of the chamber at an elevated temperature, we have contributedsubstantially to the efliciency of the process. We have found that thewalls of the chamber should be maintained substantially equal to, orslightly above, the temperature of the conglomeration of fluids at thepoint of introduction into the chamber. By maintaining the walls atatemperature as thus described, we have fulfilled two conditionsnecessary for successful operation. In the first place, for successfuloperation, there must be no flow of heat from the conglomeration, orfrom the vaporized volatile portion, to the wall. To allow such flow ofheat would result in condensation of the volatilized portion with theresult that the vaporized portion would be returned to the treatedmaterial. Secondly, because a large amount of heat is required to supplyenergy for expansion of the conglomeration within the chamber and tosupply the latent heat of vaporization for the removal of the volatileportion,

fore entering into the chamber. original conglomeration may be heated toa react on supplying additional heat through the walls'of the chamber tothe conglomeration attheapoint .of the spraying and the volatilizationreduces the need for heating theoriginal conglomeration to an undulyhigh temperature in an effort to supply the heat directly to theconglomeration be- That is, the

vthe chamber as it is required.

Our invention comprehends the application of the principles explained ina manner whichis;

eflicient and economical. The preferred apparatus employed is shown inthe drawings andthe process will be understood when reference is made tothem while the'oper'ationis explained.

As will be seen, the reguisites for carrying out our process employ ameans of supplying the conglomeration through a supply line 14. Theconglomeration is pre-heated by passing through a heat exchanger l andis placed under a relatively high pressure by a pump I6. Theconglomeration then progresses to a heater H which may be convenientlyheated by electrical heating elements of any suitable design, or bysteam or other suitable devices if desired. The conglomeration is thenintroduced into an evacuated expansion chamber II byspray atomizing thesame through a spray nozzle It whereby it is dispersed into exceedinglyfine globular particles projected into the space enclosed by the chamberII. The chamber ii is maintained at sub-atmospheric pressure by means ofa vacuum pump Hi. It is desirable in many applications to use acondenser as illustrated connected between the chamber l and the vacuumpump H in order to condense the volatilized portions of theconglomeration which are carried off by the action of the vacuum pump29. 1

The chamber H is surrounded by an insulated housing IE to provide an airspace 12 which may be heated to any suitable desirable temperature byheater meanssuch as heater rods IS. The heater rods 13 may be connectedto any suitable electrical outlet and they warm the air in the space I2and thus maintain the walls of the chamber H at a temperature at leastas high ized material is indicated by the reference character 29 and isso directed by the sprayino'zzle Is that it impingesagainst afluid=:s'urface .exposingdevice 22 where the atomizedmater'ial.collectedtas a thin. film and is 'outwardly dispersed to collect in acollecting gutter 25. The collecting gutter 25 is perforated at itslower edge as illustrated by the reference character 26 in the Figure 1..-.The fluid material thus collected in the gutter 25 may drip freelythrough the openings 25 and drip downwardly in a directioncountercurrent to the direction of the spray 29 and is intercepted inthe lower portion of the chamber II by a baffle arrangement 28. Thebaflle arrangement 28 permits the returning components to flow in a thinfilm surface for an extended period of time as it progresses to thelower level of expansion chamber II which will serve as a fluid sump.The treated components are removed from the chamber I I through aconduit 33 and passed through the heat exchanger [5 ai relatively lowsub-atmospheric pressure, and

fluid deposited -upon. a .surface.

where the sensible Zheat soontained therein i'is -transferredrtoa'o'ertain extent to the incoming 'iconglomeration ias previouslydescribed. The treatewmaterials' may be maintained at :.a scon- -stantlevel in the sump :p'o'rtion of "the :chamber l l (by means of aconstant level cap 32 .positioned atthe intakeend of the conduit-3,3.

The cap 32 thus maintains a-constant level the sump portion ofthecchamber .l l to seal the conduit .33 from the action of arvacuumwithinzthe cham- -ber *H, but affords immediate removal of ithe .excessmaterialfromithe chamber *1.

Lhu's, no accumulation is present beyond theidesired: seal- =-ingi levelat any-time inithe chamber *H ItoidecreaseL-its defective sspace'orcapacity. The rprocessma-y bezcarried outxcontinu'ously withoutinterrupti'on, and "tests show that ''the process -a-n'dequipmentwafford substantially a complete separatiomas desired.

.It ;-is :of course understood, that "theJgreatest amoun't ofsurfacemaybe obtained-in a fluid material'by sprayatoniizingithe materialrather than providing a thin film-surface. However, 'achamber'suitablefor spray atomizing a liquid from .a relatively high pressure into thechamber held at which would be large enough to'permit the :spray toascend as far as possible-without striking -.any surface; would beunduly large and impractical.

Therefor, the fluid surface exposing device 22 is employed, againstwhich the spray 29 may impinge andibe interrupted in its upwarddirection. In our apparatus, "this devicel'2'2, we have found, producesthe. greatest amount of surface area for The device 22comprisestwoscreen holders 24 positioned one above'the otherandcontaining a 'multitudezof small particles :such as raschig rings,beryl saddlesyglass beads,.or other loose materials in- :cluding; glasswool, mineral-wool and steel wool. The device 22 is substantially cone'shaped'with itsvapexcextending upwardly in the 'center and thesidedescending therefromtowards the gutter 25. .Thus, the spray29impingesagainst the .device 22 and is there interrupted in its upward7 path of travel by the multitude of .smallparticles -23. The fluid.portion of theconglomeration is thus collected upon the surface of theparticles 23 andvis continuously moved from one particle to the :other"outwardly and downwardly :by the forceof theoncoming spray 29. Duringthe time when .the fluid portion of the conglomeration is thus depositedupon the-surface of theyparticles 23, it is in a very thin 'film stageand is :continuously exposed to the action 'Idf the vacuum within thechamber l l Thus, any small amount of material to be volatilized whichhas not already been removed during theatomized state between the nozzlel8 and the fluid surface exposing device 22, will be given anopportunity to volatilize and escape. Also, the small particles 23provide a ready path for the volatilized constituents to passtherethrough and be exhausted through the condenser 20 and vacuum pumpl9. Further, the remaining fluid portion which is collected in thetrough 25 and allowed to drip countercurrently to the spray 29 asdescribed, is further exposed for a period of time to the action of thevacuum within the chamber ll while running over the baflle device 28 tothe fluid pump portion of the chamber ll.

Another suitable apparatus to carry out the process is illustrated inthe Figures 3 and 4 of the drawing, and comprises a vacuum chamber 35 ofsubstantially cone shaped cross-section.

Thus, the remaining liquid components of the original contaminatedmaterial are returned to the sump portion of the chamber 35 by runningin a thin surface area from the openings 26 of the trough 25 along thetapering heated surfaces of the cone shaped chamber 35. Thus, it will beseen, that the cone shaped chamber 35 replaces and eliminates the needfor the baflle means 28. In fact, the cone shaped chamber 35 provides awarm surface upon which the returning fluid may flow in order to assurea supply of sensible heat to cause complete volatilization of thevolatile impurities.

In both the straight and the cone shaped devices, we usually provide atleast'one vision port 3| in order that the operator may visually inspectthe condition existing within the chamber.

The process and apparatus described herein has not been limited to anyspecific fluid or conglomeration of fluids, because we have found thatthe device and process is equally successful with a large number ofvarious fluids. For example, this process and equipment has been usedsuccessfully for restoring various contaminated oils such as heattransfer oil used for quenching purposes in hardening of steel,electrical insulating oil, engine oil, lubricating oil for vacuum pumpsand the like, refrigerator lubricating oils, for degasifying beverageWaters, and for degasifying and dehydrating various fluids. That is, theprocess and equipment is equally successful for removing undesirableconstituents, for dehydrating, and for degasifying. Also, it has beenfound that each fluid treated requires a different temperature,pressure, and vacuum. Thus, whereas one fluid may require a relativelyhigh preheat temperature, another fluid may actually requirerefrigeration before being atomized within the expansion chamber. In allcases, however, the walls of the expansion chambers are easily adjustedin temperature to maintain them at exactly the proper temperature toconduct sensible heat therethrough to'maintain the interior of thechamber at exactly the desirable degree of temperature while inoperation.

Although we have described our invention with a certain degree ofparticularity in its preferred form, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is: Process for fractionally separating 'contaminatingmaterials of unlike boiling points in oils, comprising the steps ofpreheating a conglomeration of oil having said materials to an elevatedtemperature, providing a chamber having side I walls'and top and bottomend walls sealed vacuum'tight, and having a fluid surface exposing meansnear the top end wall of the chamber, evacuating said chamber to asub-atmospheric pressure by withdrawing vapors from the area of thechamber between the said fluid surface exposing means and the top endwall, said elevated preheat temperature being sufficiently hightoj'vaporize at said sub-atmospheric pressure the highest boiling pointmaterial to be removed, but said temperature being below thevaporization and decomposition temperature at said sub-atmosphericpressure of the oil to be retained as a liquid, spray atomizing saidpreheated conglomeration in said chamber from a position near the bottomend of the chamber in an upward direction toward said fluid surfaceexposing means and Y simultaneously supplying sensible heat through saidside wall of said chamber, said sensible heat being suflicient in valueto maintain the side wall of said chamber at a tempera ture at least ashigh as the boiling point within the chamber of the highest boilingpoint constituent to be removed to prevent condensation thereof, andbeing sufficient in value to supply the heat of vaporization absorbed byvolatilization of the constituents to be removed, which sensible heatvalue together with the heat units in the heated oil itself provide fullseparation of the contaminants from the oil without overheating anddestroying the oil, intercepting the remaining liquid oil portion ofsaid conglomeration on said fluid surface exposing means, saidintercepted liquid oil portion thereby being exposed to the action ofsaid sub-atmospheric pressure and to said sensible heat for a period oftime as a thin film upon the fluid surface exposing means, returning theintercepted liquid oil by gravity in a countercurrent direction to theoriginal spray direction to the bottom end of the chamber, andwithdrawing from the chamber the collected liquid oil in the bottom ofthe chamber.

CHARLES J. EGGER. ROBERT H. WEBSTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,824,498 Rodman Sept. 22, 19311,836,338 Rodman Dec. 15, 1931 1,951,739 Rodman Mar. 20, 1934 2,278,543French Apr. 7, 1942 2,332,215 French Oct. 19, 1943 2,357,829 IttnerSept. 12, 1944

